World No 3 Novak Djokovic believes Roger Federer and Rafael Nadal's grand-slam
dominance is close to an end.

Grand slam record holderRoger Federer and reigningAustralian Openchampion Rafael Nadalhave shared 20 of the past 24 grand slam titles on offer and are the two favourites heading into the Australian Open which begins tomorrow.

There has, however, been speculation their hold over the majors could be loosening, especially after 21-year-old Argentinian Juan Martin del Potro won the US Open in September.

Nadal heads to Melbourne Park having not won a singles title in eight months while there is speculation Federer may find it harder to maintain his steely focus after he became a father last year.

And with the likes of Del Potro,Andy Murray, Nikolay Davydenko and Djokovic, who won the Australian Open two years ago, on the rise the Serbian believes men's tennis is more competitive than it has ever been during the Federer-Nadal era.

"The last five, six years the dominance was obvious from Federer, Nadal," Djokovic said. "They've been winning all the grand slams they've played. But now in last two years or so the things are changing a little bit.